Breakdown test MQXFB coil 127

Tuesday 24 Mar 2026, 10:00 → 12:00 Europe/Zurich

 

Thank you for yesterday’s discussion on the breakdown and complementary tests on MQXF coils. Here below my notes:

 

• The main objective of the breakdown test campaign is to collect statistical data on the coil’s insulation system and assess margin to respect of test and operational voltages. Additional tests should not “age” or significantly alter the insulation system prior the breakdown test.
• The full list of coils and description of the NC can be found here: https://indico.cern.ch/event/1599882/. Only those marked in orange are concerned.

• Breakdown tests of CR127 are completed (see https://edms.cern.ch/document/3366449/1). The QH-to-coil insulation is still intact (withstand up to 15 kV). The ElQA team could use this coil to experiment with QH polarity measurements before it is scrapped.
• Tests on CR124 will start Wednesday next week (1/04). Breakdown test procedure will be the same as for CR127. It was agreed to interpose Capacitive Discharge (CP). Transfer Function Measurement (TFM) and Time-Domain Reflectometry (TDR) between two consecutive breakdown tests.
• For CR124, Marvin will support for TFM assuring alignment between LMF and SM18 procedures ( Hioki instrument);
• Mateusz and/or Greg will support on the TDR measurements and may lend the device for measurements of the next coils.
• Some doubts were raised regarding the applicability of TDR, as it would likely require more extensive development starting from smaller coils in a laboratory environment. Although it could be interesting, ElQA priorities do not currently allow these tests to be pursued in the near future. Nevertheless, it was decided to attempt TDR measurements on CR124. In parallel, Roland will look for MQXFS or SMC coils to further investigate TDR.

 

Roland